To improve the efficiency of conventional ventilation and/or heating systems separate heat exchange units, such as those disclosed in U.S. Pat. No. 4,653,574 issued Mar. 31, 1987 to Quinlisk et al, U.S. Pat. No. 5,257,736 issued Nov. 2, 1993 to Roy, U.S. Pat. No. 5,855,320 issued Jan. 5, 1999 to Grinbergs, and U.S. Pat. No. 6,169,849 issued Jan. 2, 2001 to Schmidt have been provided to preheat incoming fresh air with outgoing exhaust air. Conventional heat recovery units are designed to operate simultaneously with a primary heating system, e.g. furnace, and therefore require their own heat exchanging core, ductwork, dampers and control.
An object of the present invention is to overcome the shortcomings of the prior art by providing an integrated heating device with a combined furnace and heat recovery ventilator, which uses the same heat exchanger and fans for heating return air with a primary heating device, and for warming return air with warm and humid exhaust air.